I. Technical Field
This invention pertains to telecommunications, and particularly to the transport of user data in a Multimedia Broadcast/Multicast (MBM) session.
II. Related Art and Other Considerations
The Multimedia Broadcast/Multicast Service (MBMS) is a point-to-multipoint service in which data is transmitted from a single source entity to multiple recipients. Transmitting the same data to multiple recipients allows network resources to be shared.
Multimedia Broadcast/Multicast Service (MBMS) is described in one or more of the following (all of which are incorporated herein by reference in their entirety):
3GPP TS 25.433 V7.1.0 (2006-06), 3rd Generation Partnership Project, Technical Specification Group Radio Access Network, UTRAN Tub interface Node B Application Part (NBAP) signaling, (Release 7) [hereinafter, “3GPP TS 25.433 V7. 1.0”];
3GPP TS 25.346 V7.2.0 (2006-09), 3rd Generation Partnership Project, Technical Specification Group Radio Access Network, Introduction of the Multimedia Broadcast Multicast Service (MBMS) in the Radio Access Network (RAN), Stage 2, (Release 7);
3GPP TS 22.146: “Multimedia Broadcast/Multicast Service; Stage 1”;
3GPP TS 22.246: “MBMS User Services; Stage 1”;
3GPP TS 23.246: “Multimedia Broadcast Multicast Service; Architecture and Functional Description”;
3GPP TR 25.992: “Multimedia Broadcast Multicast Service (MBMS); UTRAN/GERAN Requirements”;
3GPP TS 33.246: “3G Security; Security of Multimedia Broadcast/Multicast Service (MBMS)”.
FIG. 1 illustrates an example telecommunications system 110 which facilitates a Multimedia Broadcast/Multicast Service (MBMS). The telecommunications system 110 includes a radio access network (RAN) 111. A MBMS Service Context (BM-SC) 112 contains the necessary information for the radio access network (RAN) 111 to control the MBMS service in radio access network (RAN) 111. The MBMS Service Context (BM-SC) 112 is connected through a core network (CN) 114 to the radio access network (RAN) 111. The core network 114 can comprise a Gateway GPRS Support Node (GGSN) and, in some implementations, a SGSN node (with the SGSN node connected between the GGSN node and the radio access network (RAN) 111). Alternatively, in the case of a “one tunnel” implementation, the user plane might not go via SGSN but the control plane always does.
The radio access network (RAN) 111, which can be a Universal Mobile Telecommunications (UMTS) Terrestrial Radio Access Network (UTRAN), comprises a radio network controller (RNC) node 126 and at least one radio base station node, also known as a “Node-B” or “B Node” 128 (see FIG. 2). The Node-B 128 can serve one or more cells, cells C1 through C3 being illustrated in FIG. 1 and FIG. 2. User equipment units (UEs) 30, also known as mobile stations or mobile terminals, communicate with Node-B 128 over a radio or air interface using a respective cell.
The Multimedia Broadcast/Multicast Service (MBMS) utilizes several types of bearers. An MBMS Iu data bearer is the data bearer established between a core network 114 (such as a SGSN node or GGSN node) and radio network controller (RNC) node 126 to transport MBMS data. A MBMS radio bearer is the data bearer established between the radio network controller (RNC) node 126 and the user equipment units 130 to transport MBMS data. A MBMS RAB refers both to the MBMS Iu data bearer and the MBMS radio bearer.
A Multimedia Broadcast/Multicast Service (MBMS) session has several channels, including the following: MCCH (MBMS point-to-multipoint Control Channel); MICH (MBMS Notification Indicator Channel); MSCH (MBMS point-to-multipoint Scheduling Channel); and MTCH (MBMS point-to-multipoint Traffic Channel). FIG. 1 shows a MTCH 134 between radio network controller (RNC) node 126 and each illustrated cell, FIG. 2 shows that a MTCH 134 exists between Node-B 128 and each cell served by the Node-B 128.
FIG. 2 shows an Tub bearer 136 which exists over an Tub interface, i.e., over an interface between radio network controller (RNC) node 126 and Node-B 128. A FACH transport channel mechanism is used over the Tub interface for Tub bearer 136.
A Multimedia Broadcast/Multicast Service (MBMS) session is started by a MBMS Session Start Request message sent from a core network node to radio network controller (RNC) node 126. The MBMS Session Start Request message includes such information as the MBMS Service ID, the MBMS Bearer Service Type and MBMS Session Attributes. The MBMS Session Start Request message triggers the radio network controller (RNC) node 126 to notify the user equipment units 130 (i.e., the user equipment units which have activated the MBMS Service) of the MBMS Session Start. The MBMS Session Start Request message contains the information necessary to setup the MBMS RAB.
Upon receiving the MBMS Session Start Request, the radio network controller (RNC) node 126 performs numerous activities, including execution of a NBAP (Node B Application Part) protocol. The NBAP (Node B Application Part) protocol provides, among other functions, Common Transport Channel Management. This function gives the CRNC (e.g., the radio network controller (RNC) node 126 in the illustrated scenario) the possibility to manage the configuration of Common Transport Channels in a Node B. Elementary procedures controlled by the Common Transport Channel Management include a Common Transport Channel Setup Procedure; a Common Transport Channel Reconfiguration Procedure, and a Common Transport Channel Deletion Procedure.
The Common Transport Channel Setup Procedure is described, e.g., 3GPP TS 25.433 V7.1.0 §8.2.1. The Common Transport Channel Setup Procedure is used for establishing the necessary resources in Node B, regarding Secondary CCPCH, PICH, PRACH, AICH [FDD], FACH, PCH, RACH and FPACH [1.28 Mcps TDD]. Messages included in the Common Transport Channel Setup Procedure include a COMMON TRANSPORT CHANNEL SETUP REQUEST message; a COMMON TRANSPORT CHANNEL SETUP RESPONSE message; and a COMMON TRANSPORT CHANNEL SETUP FAILURE message. The Common Transport Channel Setup Procedure is initiated with the COMMON TRANSPORT CHANNEL SETUP REQUEST message sent from the CRNC to the Node B using the Node B Control Port.
The COMMON TRANSPORT CHANNEL SETUP REQUEST message is described, e.g., in §9.1.3 of 3GPP TS 25.433 V7.1.0 (2006-06). If the COMMON TRANSPORT CHANNEL SETUP REQUEST message contains a FACH Parameters IE, the Node B shall configure and activate the indicated FACH(s) according to the COMMON TRANSPORT CHANNEL SETUP REQUEST message. If the COMMON TRANSPORT CHANNEL SETUP REQUEST message includes the Transport Layer Address and Binding ID TEs, the Node B may use the transport layer adress and the binding identifier received from the CRNC when establishing a transport bearer for the indicated common transport channels.
After successfully configuring the requested common transport channels and the common physical channels, the Node B stores the value of Configuration Generation ID IE and it shall respond with the COMMON TRANSPORT CHANNEL SETUP RESPONSE message with the Common Transport Channel ID IE, the Binding ID IE and the Transport Layer Address IE for the configured common transport channels.
A separate Common transport channel Setup procedure is required to establish MTCHs in different cells. In other words, if MTCHs to be establish in three cells C1-C3 served by the same Node-B, then three separate Common Transport Channel Setup Request messages are initiated by the radio network controller node, one such message for each cell. Thus, FIG. 2 shows existence of three common transport channels 1361, 1362, and 1363 between radio network controller (RNC) node 126 and Node-B 128. These common transport channels 136 are also know as MBMS Tub bearers and, for conventional practice, essentially correspond to the three MTCHs.
Thus, presently there is one common transport channel 136 for each cell C served by Node-B 128. In other words, common transport channel 1361 is associated with cell C1, common transport channel 1362 is associated with cell C2, and common transport channel 1363 is associated with cell C3. Thus, as depicted in FIG. 2, currently there is a need for radio network controller (RNC) node 126 to establish dedicated Tub transport resources including a dedicated Tub bearer 136 (used to carry the same MBMS user data session) for each of different cells controlled by the same Node B.
What is needed, therefore, and an object of the invention, is one or more of methods, techniques, and apparatus for efficiently providing MBMS user data transport to a Node-B which serves plural cells.